1. Field of the Invention
The invention relates to a grip for a writing instrument that is fitted to a cylinder barrel of a writing instrument such as a ball point pen, a mechanical pencil, or the like.
2. Description of Background Information
A prior art grip for a writing instrument is a cylinder constructed of a resilient material such as rubber, synthetic resin, or the like, wherein the grip is installed at an extremity of the writing instrument so as to improve the feel when the writing instrument is held with the fingers (discussed in Japanese Patent Publication No. Hei 7-20752).
Another known grip discusses a plurality of plate-like protrusions formed at an outer circumferential surface of the grip (discussed in Japanese Patent Laid-Open No. Hei 10-181274).
The grip of Hei 7-20752 is constructed such that the thickness of the cylinder is uniform over the entire length thereof.
The grip of Hei 10-181274 is constructed such that the height of the plate-like protrusions at the rear section of the grip is high, the outer diameter is large, and the height of the plate-like protrusions decreases toward the front section of the grip and its outer diameter is smaller than at the rear, as shown in FIG. 2 of this Japanese patent document.
Although such a prior art grip has a length corresponding to holding positions which are different in response to different users, the actual holding location ranges from a location near an intermediate part of a longitudinal direction (axial direction) to its forward section (i.e., toward the writing tip of the instrument). That is, as a result of performing an actual test for 50 users, even 48 persons held the grip at a range from the aforesaid location near an intermediate part to its forward section. In other words, only two persons held the grip at a point ranging from a location near the intermediate part of the grip to its rear section. As a person showed fatigue after writing for a long period of time, it was shown that the fingers slid to a forward section of the grip.
Accordingly, the prior art grips described in Hei 7-20752, in which a cylinder having substantially the same thickness over its entire length, and Hei 10-181274, in which an outer diameter decreases toward the front section, had problems such that they each have a surface structure that causes the fingers to easily forwardly slip after fatigue in writing many hours.